I operate a water treatment plant for drinking water. We use Birm® as a medium for the reduction of dissolved iron and manganese compounds from well water, followed by a sand and finally a carbon filter.
Our problem it that we have lots of algae in the product tank.
How do I stop the algae from forming? Which substances and treatment methods do you use and what are your experiences?
Hi, Kurita has good slime control agent called KURIVERTER IK-110 and it has shown good removal capability of algae in water system. Why not you send one PM to me and i can send you some information.
I think you have poor or no disinfection of the treated water and/or the inside of treated water storage tank receives sunlight that help algae growth at poor residual of disinfectant.
SaferEx an innovation and invented chemistry by us at MACJAMES Company, that efficiently disinfects, sediments metals that cause hardness (Calcium and Magnesium) and staining (Iron and Manganese), Particles, and salts, removes colour, odour and taste in "a single application and unit process" at cost and time efficiency. You can contact us: info@macjamesglobal.com for inquiries.
I think you need a multi barrier approach for this. First you need to reduce nutrient levels in your water and especially phosphorous. A proper coagulant dose ahead of your sand filter can lower phosphorous concentration. Another way is to biologically activate your media filters to consume the nutrients which might help with the problem. Finally you need to dose chlorine ahead of your product tank and prevent light from entering it to limit algae growth. Also make sure to properly clean and disinfect the tank before reusing it as adding chlorine to the tank with too much algae into it can release intercellular algal compounds which can be harmful.
You did receive nice suggestions here considering chemicals, storage conditions, nutrients concentration and new equipments. I just want to add two more options, assuming that you already have algae contamination in raw water:
1- Evaluate a DAF as a pre treatment (or maybe as a clarifier, as well)
2- I am doing some research about ultrasonic aplication in raw water, also to reduce the upstream contamination.
I wasn't familiar with Birm so I did a search. Go to https://www.cleanwaterstore.com/resource/frequently-asked-questions/about-birm-iron-filters/.
Based on the information at this site, it appears Birm is not the best selection for removing the manganese. However, your issue is algae. Have you measured the phosphorous concentration? Is your product tank and/or filters exposed to sunlight? After running the water through the Birm, what is the dissolved oxygen concentration? If it is near 0 and the detention in the product tank is long w/ exposure to sunlight and there is significant phosphorous, algae will be produced. If the filters/product tank are not covered, can you cover them? If the dissolved oxygen is near 0, I would suggest aerating the water to at least 1 ppm.
As some of the others have said, ozonation and chlorination would work. However, if the tanks are exposed to sunlight, I wouldn't coat the walls a dark color. Having personal experience with dark colored hypalon liners in wastewater lagoons, the liners heated the water in March in cold Colorado and algae formed. Coating the walls a dark color w/ exposure to sunlight would only aggravate the algae problem.
Chlorine would be your best bet, as it would also act as an Anti-Bacterial. UV would not be as good due to filming on the Quartz Tube which would then block the UV rays.
For this purpose Ozonation is the best method to reduce the algae. It has good results at low price. Chlorine is also a good option but it is difficult in handling and dosing.
No! Ozonation will kill the cells and lyse them and release the toxins that might be present,. Ozonation or chlorine can be applied to the water after the algal cells have been filtered out and they will react with some toxins, like microcystin-LR.
Chlorine will certainly slow down or kill off algae with the right dosage.
Other suggestions
If you can stop sunlight entering the product tank you will stop the growth of all algae. Shading will slow them down.
You don't say if the problem is due to attached or planktonic (floating) species or but I assume you will have low water residence time in the product tank so probably attached algae (filaments) as the planktonic species will be washed out. So a good scrub of the walls and floor along withthe chlorine if you have attached forms.
You should treat to reduce the amount of Nitrogen in your system. This will also lower the BOD. This can be done by introducing a series of Aerobic or Anaerobic microbes. Depending on your situation, you could also experience a reduction in odor and reduction of Phosphorus as well. We work with 300 different species of microbes both aerobic and anaerobic and will put together a consortium of microbes that will reduce Nitrogen very rapidly.
I would suggest addition of chlorine, enough to leave a residual concentration in the product water, inhibiting algal growth. If chlorine is not feasible, maybe UV light could be used to inactivate the algal cells which are getting through the process.